A feat represents a talent or an area of expertise that gives a character Special capabilities. It embodies Training, experience, and Abilities beyond what a class provides.
As a PC levels, they gain a total of 11 feats (without multiclassing). Every class gains feats at class levels: 2, 4, 6, 10, 14, 18, 22, 26, 30, 34, and 38.
You must meet any prerequisites in order to take that feat. If you ever lose a feat’s prerequisite, you can’t use that feat until you regain the prerequisite. For example, the Grappler feat requires you to have a Body of 1 or higher. If your Body is reduced below 1 somehow—perhaps by a withering curse—you can’t benefit from the Grappler feat until your Body is restored.